There is no direct FOR-MIA flight on Sunday 3rd Nov (there is a direct flight on Monday 4th though).
That's why it's not coming up.
The flights you see on Latam all have a stop.
So you would need to search for each of those flights individually on BA if you really want to come back on the 3rd.
If you ring up BA they can ticket all 3 flights on one PNR but you can't do it online.
BA will charge you avios for each flight individually so it will be more expensive, but maybe not greatly so as short Latam flights aren't very expensive in Avios.